A French scientist’s temperature data show results different from the official climate science. Why was he stonewalled? Climate Research Unit emails detail efforts to deny access to global temperature data.

The global average temperature is calculated by climatologists at the Climatic Research Unit (CRU) at the University of East Anglia. The temperature graph the CRU produces from its monthly averages is the main indicator of global temperature change used by the International Panel on Climate Change, and it shows a steady increase in global lower atmospheric temperature over the 20th century. Similar graphs for regions of the world, such as Europe and North America, show the same trend. This is consistent with increasing industrialization, growing use of fossil fuels, and rising atmospheric concentrations of carbon dioxide.

It took the CRU workers decades to assemble millions of temperature measurements from around the globe. The earliest measurements they gathered came from the mid 19th century, when mariners threw buckets over the side of their square riggers and hauled them up to measure water temperature. Meteorologists increasingly started recording regular temperature on land around the same time. Today they collect measurements electronically from national meteorological services and ocean-going ships.